Surface Interactions of Oxygen Suffice to P‐Dope the Halide Perovskites

Abstract Attempts to dope halide perovskites (HaPs) extrinsically have been mostly unsuccessful. Still, oxygen (O₂) is an efficient p‐dopant for polycrystalline HaP films. To an extent, this doping is reversible, i.e., the films can be de‐doped by decreasing the O₂ partial pressure. Here results are reported, aimed at understanding the mechanism of such reversible doping, as it has been argued that doping involves interaction of oxygen with defects inside bulk HaP. These experimental results clearly point out that O₂‐surface interactions suffice to dope the bulk of the films. Such behavior fits what is known for other polycrystalline semiconductors, where surface charge transfer‐adducts can form and be removed. Thus, controlling the O₂ partial pressure to which the HaP film is exposed, can, after proper encapsulation, achieve the desired bulk doping of the film.